As a solution to recent demands for mass production and cost reduction of optical modules, a mounting technique in which optical devices are hybridly integrated onto an Si platform or a PLC (Planer Lightwave Circuit) platform, is attracted.
In particular, in mounting technique (a planer mounting technique) which uses a PLC platform as a mounting substrate, optical devices are mounted on a common substrate wherein a waveguide has been formed on the surface. Therefore, this technique is suitable for downsizing an optical module and for simplifying the assembly process.
Further, in mounting an optical device onto a platform, an alignment operation is generally performed by active alignment technique in which the position of an optical device is adjusted while monitoring an actual optical coupling efficiency.
Following patent references 1-3 can be regarded as prior art related to the embodiment.
Patent reference 1 discloses a technique of controlling the beam diameter at a focus by filling a coupling between a lens and an optical waveguide with liquid. Patent reference 2 discloses a technique of controlling an incidence angle by filling the input section of an oblique-incidence optical receiving device with a liquid. These patent references however do not disclose a technical concept of using a filled liquid as a waveguide.
Further, patent reference 3 discloses a technique of a tube-shaped waveguide which is formed between a lens and a laser diode (LD) and which is made on a transparent rubber to realize a position-shift-proof structure.
Patent reference 1: Japanese Patent Application Laid-Open (KOKAI) Publication No. HEI 1-253705
Patent reference 2: Japanese Patent No. 3549086
Patent reference 3: Japanese Patent Application Laid-Open (KOKAI) Publication No. 2004-233896